(display "\n========================================\n")
(define x (list (list 1 2) (list 3 4)))
(display x)
(newline)
(display (cadr x))
(newline)

(define (fringe items)
    (cond ((null? items) '())
          ((pair? items)
            (append (fringe (car items))
                    (fringe (cdr items))))
          (else
            (list items))))

(display (fringe (list x x x 0 0 0 0)))
(display "\n========================================\n")
